An in-depth analysis of traffic stop data as part of the state's racial profiling law has revealed a "statistically significant racial or ethnic disparity," in stops by the Groton Town Police Department.

Groton was among five law enforcement agencies identified in a report as having data that warranted further analysis to determine if any racial or ethnic bias exists. The report was issued Tuesday by the Institute for Municipal and Regional Police at Central Connecticut State University.

The report is an evaluation of a year’s worth of traffic stop data gathered between Oct. 1, 2013 and Sept. 30, 2014. Statewide, more than 620,000 traffic stops were conducted by more than 100 municipal and state agencies.

Data is being collected electronically on a monthly basis as part of the updated Alvin W. Penn Racial Profiling Prohibition Act, which was first enacted in the state in 1999. The law prohibits law enforcement from stopping, detaining or searching motorists based on race, ethnicity or sexual orientation.

Ken Barone, a policy and research specialist for the institute, said the report is the most comprehensive examination of police traffic stops in the country. He said Groton Town, Granby police, Waterbury police and state police Troops C in Tolland and H in Hartford were all identified through certain statistical tests as displaying disparities.

Groton was singled out in part because of data revealed in the so-called "Veil of Darkness" test, which measures the number of minority motorists stopped in daylight compared to those arrested after dark, when the officer cannot initially distinguish race.

Barone said data from traffic stops is taken from times of the morning and evening throughout the year when it is dark or light. The numbers are compared and measured against statewide data.

Barone said further study will be conducted in Groton to help pinpoint the cause of the disparities, which in some cases could be driven by individual officers or department policies. The review could lead to revision of policies or training for officers at the department

In the area covered by Groton Town Police, which does not include Groton City or Groton Long Point, 23.7 percent of drivers stopped by Groton Town officers were minorities — 8.3 percent Hispanic, 13.6 percent black and 1.8 percent other.

Groton Town Police Capt. Steven Sinagra said department officials have already made arrangements to meet with the authors of the study “to figure out what it all means and to address whatever issues may exist.”

Sinagra said the department has been collecting and submitting data to the state for years without any indication of an issue.

The report warns that while numbers may “signal the potential of racial profiling,” they cannot, without further study, lead to a conclusion that racial profiling exists.

“Certain factors may be driving these disparities (in Groton), but this is a very strict test,” Barone said. “The likelihood that it would show a false positive is very unlikely.”

The Norwich Police Department was identified in the report as one of five police departments where stop data exceeded the “disparity threshold levels,” when data was compared to certain benchmarks in statewide data, estimated driving population, resident-only stops and surrounding departments.

Norwich Deputy Chief Patrick Daley issued a press statement addressing the study.

“The data, which the police department is just beginning to study, has shown an area of concern,” according to the statement. “It should be noted that there are three tiers of concern level and Norwich is at the bottom of the lowest tier.”

The report recommends further monitoring, but officials said they have taken proactive measures, including a meeting with the Norwich branch of the NAACP.

Norwich police, prior to the release of the report, also started Fair and Impartial Policing training through the U.S. Department of Justice. In March, Lt. James Veiga and Sgt. Michael McKinney became state instructors.

The New London Police Department, because of technical difficulties, began submitting data on March 1, 2014 instead of Oct, 1, 2013.

The data submitted by New London showed they lead the state in the percentage of traffic stops that led to arrests and were at the top of the list of departments whose traffic stops led to searches.

Statewide, less than 1 percent of traffic stops led to an arrest and 2.9 percent resulted in searches. In New London, 7.3 percent of stops resulted in an arrest. The next closest department was West Hartford with 5.9 percent. The report shows that 8.5 percent of traffic stops in New London led to searches, the fourth highest in the state.

An analysis by The Day in 2013 of the so-called yellow cards that police officers filled out after traffic stops showed that blacks and Hispanics pulled over by New London police were nearly twice as likely as whites to have their vehicles searched. That analysis was of motor vehicle stops in 2011, the most recent data available at the time.

The analysis showed, however, that minorities were not over-represented in traffic stops.

Researchers said 33 of the state's 102 law enforcement agencies had disparities in their data showing minorities were stopped at higher rates than whites, according to population and other statistics.

The report released Tuesday is the result of work first outlined by the Racial Profiling Project Advisory Board established in 2012 by the state Office of Policy and Management. The Institute for Municipal and Regional Policy at CCSU oversaw the number crunching and management of the study. The institute worked with the state’s Criminal Justice Information System to develop a system that allows law enforcement agencies to submit traffic stop data electronically on a monthly basis.

The entire report is available at www.ctrp3.org.

g.smith@theday.com

Twitter: @SmittyDay